Improvement in zincing iron



F. A'. KRAFT.

ZinCing Bath.

Patented June 23, 1868.

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Letters Patent 1V0. 79,234, dated June 23, 1868.

IMPROVEMENT IN ZINGING IRON.

@lgc Stlgchnle numb in in flpzst Etcttcts hated mu making and of tip same.

TO ALL WHOM IT MAY CONCERN: I

Be it known ,thatl, FREDERICK A.,KnAFT, of Philadelphia, Pennsylvania, have invented an Improved Zincing-Bath; and I do hereby declare the following to be a full, clear, and exact description of thesame.

My invention relatesto the z incing of articles of iron or other metal, by immersing them in molten zinc; and my invention consists of a zincing-bath composed of an outer casing of iron lined with copper or equivalent material, for preventing the formation of a drossfrom the iron and zinc, which tends to destroy the iron vessel, and renders a grcat portion of the zinc unfit for coating purposes.

I will now proceed to describe a mode of carrying the same into effect, reference being had to the accompanying drawing, which'forms a part of this specification, and in which- Figure 1 represents a portion (full sizc'd)'of a zincing-bath.

Figure 2, a transverse section of the bath, drawn to a reduced scale of oni'e inch to a foot.

In conducting the process of coating iron with'zinc, it has been usual to employ cast or wrought-iron vessels for containing the zinc, which is maintained in a moltcnlcondition by the application of external heati Vessel's'of the smaller size are occasionally made of cast iron, but those of larger size of thick wrought-. iron plates.

For a vessel tweiveieet long, twenty-six inches wide, and forty inches deep, for instance, wrought-iron plates one inch in thickness are necessary, to withstand the pressure of the zinc, a coke fire contained in a recess continued on all sidesof the vessel, being used formaintaining the zinc at or about the tcmpcratu rc of 750 Fahrenheit.

Owing to the intimate contact of the zinc with theiron, and to the heat to which both are subjected, the two metals oxidize rapidly, forming what is known as speltcr-dross, which settles on the bottom 'of the vessel, and the greater the heat the faster does this so-called dross accumulate.

l The evils resulting from the formation of this dross in ordinary zincing-baths may be enumerated as follows:

Firs t, the reduction of the'zinc to the condition of dross, useless for coating purposes, and ofhalf the value of the pure zinc, to the condition of which it cannot. be restored without resorting to tedious and expensive processes.

Second, the rapid destruction of costly wrought-iron vessels; and

Third, the tedious manipulation demanded in removing the dross from the pure zinc.

In order to obviate these evils, I line the cast or wrought-iron vessel with a. material which, at the temperature to which it is"usually subjected, will not be affected by or form an alloy with the zinc, or which will not so readily form an alloy with the hitter as iron. I i

In fig. 1, of the drawing, Arepresents a portion of the outer casing of wrought iron, and B a thin lining of copper, rivetedto the outer casing at suitable intervals. i 7

It is not necessary, in order to maintain the zinc in' a. proper molten condition, to heat it above 750 or 800, and as atith'is temperaturc no combination can he efi'ectcd between copper and zinc, the formation of dross, in a vessel lined with copper or equivalent material, cannot takeplace.

'lhrough carelessness, however, the vessel may be heated to such an extent that the copper would form an alloy with the zinc; but as a provision against such accidents, the surface of the copper exposed to the zinc may have a thin coating of silver, which, although it can be melted at a less heat than copper, has not such an affinity as the latter for zinc.

The interior of the vessel maybe lined with thin fire-tiles in place of copper, the tiles being secured by copper or other fastcnings, or slabs of slate, or glass or earthenware may be used for lining-purposes, with good results as regards preventing the formation of the above-mentioned dross; or the intcrior'of the vessel may be lined at the sides with copper, and at the bottom with fire-tiles, slate, glass, Etc.

I claim as my invention, and desire to secure by Letters Patent- A zincing-bath, composed'ot' an outer casing of iron, containing an'inner lining or casing of copper or its equivalent, as set forth. I

In testimony whereof,I have signed my nameto this specification in the presencc of two subscribing witnesses.

FRED. A. KRAFT.

Witnesses:

Win. A. STEE HARRY SMITH. 

